Diminished activity oftartrate resistant acid phosphatase inalveolar macrophages frompatients withactive sarcoidosis

Alveolar macrophages differ fromtheir percursorsinblood, monocytes, byexpressing strong activity ofthetartrate resistant variant ofacid phosphatase (TAcP). Astudy wascarried outto analyse theexpression ofthis enzyme cytochemical markerbyalveolar macrophages from bronchoalveolar lavage cells from34patients withsarcoidosis and12control subjects. Alveolar macrophages fromcontrol subjects displayed a strongandhomogeneous staining pattern andonly 0-1%ofcells were negative after staining. Macrophages frompatients withsarcoidosis showed reduced TAcPactivity andup to7% ofthecells werenegative. Thepercentage ofTAcPnegative macrophages was correlated withthepercentage oflymphocytes andwiththeratio ofCD4toCD8 lymphocytes among cells recovered bybronchoalveolar lavage. Thereduced TAcPactivity in alveolar macophages frompatients withsarcoidosis may beduetoan increased recruitment of immature precursorsfromblood.